Semiconductor device having engineering change order (eco) cells

ABSTRACT

A semiconductor device including: standard functional cells located in a logic area; standard spare cells arranged in a spare region of the logic area; and a metallization layer including segments, some of the segments being included in corresponding ones of the functional cells, some of the segments being included in corresponding ones of the spare cells, and some of the segments representing strap lines; and wherein a first pitch of the standard spare cells is based on a second pitch of the strap lines.

PRIORITY CLAIM

The present application is a divisional of U.S. application Ser. No.15/370,418, filed Dec. 6, 2016, which claims the priority of U.S.Provisional Application No. 62/402,953, filed Sep. 30, 2016, which areincorporated herein by reference in their entireties.

BACKGROUND

An integrated circuit (IC) includes a number of electronic devices. Oneway in which to represent the IC is as a layout diagram (hereinafter,layout). A layout is hierarchical and is decomposed into modules whichcarry out higher-level functions as required by the IC's designspecifications. In some circumstances, a semi-custom design (SCD)project decomposes the modules into macro cells, standard cells andcustom cells.

For a given SCD project, a custom cell is designed with an arrangementthat is specific to the given SCD project in order to provide (inoperation) a higher-level logic function that is specific to the SCDproject. By contrast, a library of standard cells is designed with noparticular project in mind and includes standard cells which provide (inoperation) common, lower-level logic functions. In terms of a footprintwithin a layout, custom cells are larger (typically much larger) thanstandard cells. Moreover, for a given library, all of the standard cellshave at least one dimension which is the same size (typically, the sizebeing a multiple of a library-specific fixed dimension) in order tofacilitate placement of the standard cells into a layout. As such,standard cells are described as being predefined with respect to a givenSCD project. Custom cells may or may not have at least one dimensionthat is the same size as the corresponding dimension of the standardcells.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

Figure (FIG. 1A is a layout, for a semiconductor device, of engineeringchange order (ECO) base cells relative to line segments, in accordancewith some embodiments.

FIG. 1B is a layout, corresponding to the layout of FIG. 1A, ofallotment of metallization segments to corresponding maskingpatterns/colors, in accordance with some embodiments.

FIG. 1C is a layout, corresponding to the layout of FIG. 1A, of reservedregions in the ECO base cells, in accordance with some embodiments.

FIG. 2 is a layout, for a semiconductor device, of reserved regions inthe ECO base cells, in accordance with some embodiments.

FIG. 3A is another layout, for a semiconductor device, of reservedregions in the ECO base cells, in accordance with some embodiments.

FIG. 3B is a simplified version of the layout of FIG. 3A, in accordancewith some embodiments.

FIG. 3C is another simplified version of the layout of FIG. 3A, inaccordance with some embodiments.

FIG. 4A is a layout, for a semiconductor device, of ECO base cellsrelative to line segments, in accordance with some embodiments.

FIG. 4B is a simplified version of the layout of FIG. 4A, in accordancewith some embodiments.

FIG. 4C is another simplified version of the layout of FIG. 4A, inaccordance with some embodiments.

FIG. 5A is a layout, for a semiconductor device, of ECO base cellsrelative to line segments, in accordance with some embodiments.

FIG. 5B is a simplified version of the layout of FIG. 5A, in accordancewith some embodiments.

FIG. 5C is a simplified version of the layout of FIG. 5A, in accordancewith some embodiments.

FIG. 6A is a flowchart of a method of designing, for a semiconductordevice, a layout, in accordance with some embodiments.

FIG. 6B is a detailed view of a block in the flowchart of FIG. 6A, inaccordance with some embodiments.

FIG. 6C is a detailed view of another block in the flowchart of FIG. 6A,in accordance with some embodiments.

FIG. 6D is a detailed view of another block in the flowchart of FIG. 6A,in accordance with some embodiments.

FIG. 7A is a flowchart of a method of designing, for a semiconductordevice, a layout, in accordance with some embodiments.

FIG. 7B is a detailed view of a block in the flowchart of FIG. 7A, inaccordance with some embodiments.

FIG. 7C is a detailed view of another block in the flowchart of FIG. 7A,in accordance with some embodiments.

FIG. 8 is a flowchart of a method of designing, for a semiconductordevice, a layout, in accordance with some embodiments.

FIG. 9A is a schematic view of a semiconductor device, in accordancewith some embodiments.

FIG. 9B is a schematic view of the semiconductor device of FIG. 9Arevised with one or more ECO programmed cells, in accordance with someembodiments.

FIG. 10 is a flow chart of a method of manufacturing a semiconductordevice, in accordance with some embodiments.

FIG. 11 is a block diagram of an EDA system, in accordance with someembodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components, materials, values, steps,operations, materials, arrangements, or the like, are described below tosimplify the present disclosure. These are, of course, merely examplesand are not intended to be limiting. Other components, values,operations, materials, arrangements, or the like, are contemplated. Forexample, the formation of a first feature over or on a second feature inthe description that follows may include embodiments in which the firstand second features are formed in direct contact, and may also includeembodiments in which additional features may be formed between the firstand second features, such that the first and second features may not bein direct contact. In addition, the present disclosure may repeatreference numerals and/or letters in the various examples. Thisrepetition is for the purpose of simplicity and clarity and does not initself dictate a relationship between the various embodiments and/orconfigurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

When placing Engineering Change Order (ECO) base cells into a row of alayout, minimizing gaps between adjacent ECO base cells reduces wastedspace and increases density (in terms of the number of devices percell). Also, placement of ECO base cells into a row of a layout issimplified if the ECO base cells are fixed not merely in height but alsoin width. In some embodiments, gaps are reduced and placement of ECObase cells into a row is simplified by using a pitch of the ECO basecells, P_(ECOB) (or P_(SPARE)), which is evenly divisible into a pitchof the M1 straps, P_(M1-STRAP). In some embodiments, a strap is one ormore segments in a metallization layer which carry an operationalvoltage, e.g., VDD, VSS or the like. The first metallization layer isreferred to as M1. Hence, a strap in the M1 layer is an M1 strap. Insome embodiments, to eliminate gaps (achieve abutment) between adjacentECO base cells when placing ECO base cells into a row, pitch P_(ECOB) ofthe ECO base cells is chosen to be consistent with the even/odd statusof the number of masking patterns/colors CLR.

In the context of a semi-custom design (SCD) project, in addition tostandard cells and custom cells, macro cells may also be included.Similar to custom cells, macro cells provide a higher-level functionthan standard cells. However, similar to standard cells, macro cells aredesigned with no particular project in mind. As such, macro cells aredesigned with an arrangement which provides a higher-level logicfunction that is common, e.g., RAM, ROM, serial interface, timer,arithmetic logic unit (ALU) processor core, or the like. Macro cellshaving a higher-level function consume a larger footprint. As such,macro cells have a much larger footprint than standard cells. Some macrocells are arrangements of standard cells.

Also similar to custom cells, macro cells do not have at least onedimension that is the same size as the corresponding dimension of thestandard cells. For this reason, macro cells and custom cells will bereferred to as non-standard cells.

There are two types of standard cells, standard functional cells andstandard spare cells, the latter being referred to as engineering changeorder (ECO) cells. Standard functional cells are defined with specificinternal arrangements of components to provide (in operation)corresponding common, lower-level functions, e.g., logic functionsincluding an inverter, NAND, NOR, XOR, D-latch, decoupling capacitor(DeCap), and-or-invert (AOI), or-and-invert (OAI), multiplexer,flip-flop, or the like.

ECO cells include ECO base cells and ECO programmed cells. An ECOprogrammed cell refers to an ECO base cell which has been programmed.Similar to a functional cell, an ECO base cell is defined with aspecific internal arrangement of components. Unlike a functional cell,an ECO base cell is not arranged to provide a specific function. Incontrast to standard cells which operate (are operational), an ECO basecell (which has not yet been programmed) does not operate (is notoperational).

Recalling that ECO base cells are spare cells, the arrangement of an ECObase cell is sufficient that, if needed, the ECO base cell is able to be‘programmed’ (transformed) to operate and provide one of the same,common, low-level functions provided by a corresponding standardfunctional cell. In some embodiments, the arrangement of each ECO basecell is sufficient so that a given ECO base cell is able to be‘programmed’ (transformed) to operate and provide one of the logicfunctions including an inverter, NAND, NOR, XOR, D-latch, decouplingcapacitor (DeCap), and-or-invert (AOI), or-and-invert (OAI),multiplexer, flip-flop, or the like. In some embodiments, an ECO basecell is programmed (transformed) into an ECO programmed cell by alteringone or more connections within at least one ECO base cell(intra-ECO-base-cell connections) such as metal to silicon contacts andmetal to polysilicon contacts, or making other metal layer changes withcorresponding vias or contacts.

During an SCD project, electronic design automation (EDA) tools are usedto select standard functional cells from standard cell libraries andplace the standard functional cells into an initial layout along withnon-standard cells (if any). EDA tools are also used to perform routingby which the standard functional cells and the non-standard cells areconnected using one or more metal layers and corresponding vias andcontacts. EDA tools are further used to test the routing. Depending uponthe test results, the selection, placement and routing of the standardand non-standard cells is revised. In at least some embodiments, theoverall selection, placement, routing and testing (SPRT) process isiterative. Eventually, the SPRT process iterations converge to afinalized layout.

For a variety of reasons (e.g., a design change, an unacceptable timingissue, an unacceptable electromigration issue, or the like), it iscommon for a nearly finalized layout (or a layout that otherwise wouldhave been regarded as a final layout) to be required to undergorevision. In anticipation of circumstances in which the revision wouldbe relatively minor in scope, and as a safeguard (or hedge) againsthaving to restart (begin anew) the iterative SPRT process, EDA tools arealso used to place one or more ECO base cells into the initial layout.

Because the ECO base cells do not operate, the ECO base cells are notconnected to functional cells. When the nearly finalized layout is to berevised, one or more ECO base cells are ‘programmed,’ which converts theone or more ECO base cells into one or more ECO ‘programmed’ cells.Then, the ECO programmed cell is routed to be operatively connected toone or more standard functional cells. In some embodiments, ECO basecells correspond to ECO base cells disclosed in U.S. Pat. No. 7,137,094,granted Nov. 14, 2006, the entirety of which is hereby incorporated byreference. In some embodiments, ECO base cells correspond to ECO basecells disclosed in U.S. Pat. No. 7,458,051, granted Nov. 25, 2008, theentirety of which is hereby incorporated by reference.

FIG. 1A is a layout 100A, for a semiconductor device, of ECO base cellsrelative to line segments in an i^(th) metallization layer, M(i), inaccordance with some embodiments.

In some embodiments, the M(i) layer is M1. In FIGS. 1A-1C, M(i) is M1.

In FIG. 1A, layout 100A is of a semiconductor device which includes anIC formed on a substrate 102. Substrate 102 includes a logic area 104 inwhich standard functional cells (not illustrated) and standard ECO basecells are formed. Logic area 104 is shown as including ECO base cells106A-106F, 108A, 110A-110F, 112A, 114A-114F and 116A. Other quantitiesof ECO base cells are contemplated. For simplicity of illustration, anECO base cell is represented in FIG. 1A by its boundary. For simplicityof illustration, components and intra-ECO-base-cell connections of eachECO base cell are not shown.

As noted, for a given library, all of the standard cells have at leastone dimension which is fixed at the same size in order to facilitateplacement of the standard cells into a layout. In some embodiments, thefixed size is a multiple of a library-specific fixed dimension. In someembodiments, the fixed size is a multiple of the minimum pitch betweenpolysilicon features, P_(POLY).

In some embodiments, the standard cells (including standard functionalcells and standard ECO base cells) are polygons. In some embodiments,the standard cells are rectangular polygons. In some embodiments, fromthe perspective of a plan view, the X-axis is horizontal and the Y-axisis vertical such that the horizontal and vertical dimensions of arectangular standard cell are described as the corresponding width andheight of the cell. In some embodiments, the layout is arranged in rows,and the height of all the standard cells is the same to facilitateplacing the standard cells into the rows of the layout.

Returning to FIG. 1A, ECO base cells 106A-106F and 108A are arranged inthe horizontal direction and located in a first row 118A. ECO base cells110A-110E and 112A are arranged in the horizontal direction and locatedin a second row 118B. ECO base cells 114A-114F and 116A are arranged inthe horizontal direction and located in a third row 118C. All of ECObase cells 106A-106F, 108A, 110A-110F, 112A, 114A-114F and 116A have thesame size in the vertical direction (same height). However, otherconfigurations are within the scope of the present disclosure. In thefirst row, adjacent ones of ECO base cells 106A-106F and 108A abuthorizontally. In particular, in first row 118A, ECO base cell 106A abutsECO base cell 106B, ECO base cell 106B abuts ECO base cell 106C, and soon. In second row 118B, adjacent ones of ECO base cells 110A-110F and112A abut horizontally. In particular, ECO base cell 110A abuts ECO basecell 110B, ECO base cell 110B abuts ECO base cell 110C, and so on. Inthird row 118C, adjacent ones of ECO base cells 114A-114F and 116A abuthorizontally. In particular, ECO base cell 114A abuts ECO base cell114B, ECO base cell 114B abuts ECO base cell 114C, and so on.

To facilitate inter-cell connections, a layout comprises a stack ofplanar ‘metallization’ layers interspersed with planar inter-layerdielectric (ILD) structures. A given ‘metallization’ layer includesparallel conductive line segments. In some embodiments, the conductiveline segments are metal. In some embodiments, the parallel line segmentsin successive metallization layers are orthogonal to each other. In someembodiments, the parallel line segments in an i^(th) metallization layer(M(i)) extend in a first direction, the parallel line segments in an(i+1)^(th) metallization layer (M(i+1)) extend in a second directionwhich is orthogonal to the first direction, the parallel line segmentsin an (i+2)^(th) metallization layer (M(i+2)) extend in the firstdirection, the parallel line segments in an (i+3)^(th) metallizationlayer (M(i+3)) extend in the second direction, and so on. In someembodiments, the first direction is parallel to the X-axis, and thesecond direction is parallel to the Y-axis.

In some embodiments, the segments of the i^(th) metallization layer M(i)are regularly spaced apart, which is described as the pitch of themetallization segments, P_(MET-SEG)(i). In some embodiments, the pitchP_(MET-SEG)(i) is a multiple of the minimum pitch between polysiliconfeatures, P_(POLY).

An ILD structure provides insulation between a metallization layer whichis formed on the ILD structure and another structure on which the ILDstructure is formed. In some embodiments, the other structure is anothermetallization layer. In some embodiments, the other structure is asilicon substrate which includes, e.g., transistor components, or thelike. As such, much of an ILD structure is a dielectric material. Whenformed underneath an M(i+1) layer, an ILD structure is referred to as ani^(th) ILD structure (ILD(i)).

Where the ILD(i) is interposed between M(i+1) and M(i) layers, in orderto establish a connection between an M(i+1) segment (which extends inthe first direction) in the M(i+1) layer and an M(i) segment (whichextends in the second direction) in the M(i) layer, ILD(i) also includescontact/vias structures which extend in a third direction which isorthogonal to the first and second directions. Similarly, where i=1,ILD0 is interposed between the M1 layer and the substrate. To establisha connection between an M1 segment and a component in the substrate,e.g., a transistor component, or the like, ILD0 also includes contactstructures which extend in the third direction. In some embodiments, thethird direction is parallel to the Z-axis. In some embodiments, the M(i)layer is M1. In FIG. 1A, M(i) is M1.

As noted, the ECO base cells in layout 100A of FIG. 1A are laid out (orarranged) relative to line segments in the M1 layer. Accordingly, FIG.1A shows M1 line segments (M1 segments) as parallel rectangles 120A,120B, 122A, 122B and 124. For context, gate structures are shown inlayout 100A of FIG. 1A as parallel rectangles 130A, 130B and 132interspersed with corresponding M1 segments 120A, 120B, 122A, 122B and124.

It is noted that not all of M1 segments 120A, 120B, 122A and 122B, themultiple instances of M1 segment 124, gate structures 130A and 130B andthe multiple instances of gate structure 132 will necessarily remainafter the ECO base cells are initially formed and/or after one or moreof the ECO base cells are programmed. For example, each of M1 segments120A, 120B, 122A and 122B and gate structures 130A and 130B, each of themultiple instances of M1 segment 124, and each of the multiple instancesof gate structure 132 has the potential to remain after the ECO basecells are initially formed. Accordingly, it is contemplated that anygiven ECO base cell could have a different quantity of M1 segmentsand/or a different quantity of gate structures.

In some embodiments, the ECO base cells are initially formed using acut-last technique which includes forming all possible gate structures,removing (cutting) selected gate structures in whole or in part, formingall possible M1 segments, and removing (cutting) selected M1 segments inwhole or in part such that fewer than all of the multiple instances ofM1 segment 124 and less than all of the multiple instances of gatestructure 132 remain. In some embodiments, the ECO base cells areinitially formed using a cut-last technique which includes forming allpossible M1 segments, and removing (cutting) selected M1 segments inwhole or in part, forming all possible gate structures, removing(cutting) selected gate structures in whole or in part, such that fewerthan all of the multiple instances of M1 segment 124 and less than allof the multiple instances of gate structure 132 remain. In someembodiments, when an ECO base cell is programmed, one or more of theremaining multiple instances of M1 segment 124 are cut, thereby leavingyet fewer instances of M1 segment 124 remaining.

Each of M1 segments 120A, 120B, 122A, 122B and 124 has a shorterdimension parallel to the X-axis and a longer dimension parallel to theY-axis. As such, the long axis of each of M1 segments 120A, 120B, 122A,122B and 124 is regarded as orthogonally intersecting a correspondingone or more of rows 118A-118C. Each of M1 segments 120A, 120B, 122A and122B is sufficiently long to span (orthogonally) rows 118A-118C. Bycontrast, each M1 segment 124 is shorter in length as compared to M1segments 120A, 120B, 122A and 122B. Corresponding M1 segments in firstrow 118A, second row 118B and third row 118C align in the verticaldirection, as called out by phantom rectangle 126. Other horizontaldimensions and/or or vertical dimensions for M1 segments 120A, 120B,122A and 122B are contemplated.

In some embodiments, each M1 segment 124 is sufficiently short in lengthto not extend outside a corresponding top and/or bottom edge of one ormore of ECO base cells 106A-106F, 108A, 110A-110F, 112A, 114A-114F and116A in the vertical direction. In some embodiments, all M1 segments 124are placed so that an imaginary horizontal reference line bisecting eachM1 segment 124 is collinear with an imaginary horizontal reference linebisecting a corresponding one or more of ECO base cells 106A-106F, 108A,110A-110F, 112A, 114A-114F and 116A. Other vertical locations for M1segments 124 with respect to one or more corresponding ECO base cells106A-106F, 108A, 110A-110F, 112A, 114A-114F and 116A are contemplated.Other horizontal dimensions and/or or vertical dimensions for M1segments 124 are contemplated.

For context, gate structures 130A, 130B and 132 are shown in layout 100Aof FIG. 1A as parallel rectangles 130A, 130B and 132. Each of gatestructures 130A, 130B and 132 has a shorter dimension parallel to theX-axis and a longer dimension parallel to the Y-axis. As such, the longaxis of each of gate structures 130A, 130B and 132 is regarded asorthogonally intersecting a corresponding one or more of rows 118A-118C.Each of gate structures 130A and 130B is sufficiently long to span(orthogonally) rows 118A-118C. By contrast, each gate structure 132 isshorter in length as compared to gate structures 130A and 130B. Othervertical locations for gate structures 132 with respect to one or morecorresponding ECO base cells 106A-106F, 108A, 110A-110F, 112A, 114A-114Fand 116A are contemplated. Corresponding gate structures 132 in firstrow 118A, second row 118B and third row 118C align in the verticaldirection, as called out by phantom rectangle 134.

In some embodiments, each M1 segment 124 is sufficiently short in lengthto not extend across a corresponding one or more of ECO base cells106A-106F, 108A, 110A-110F, 112A, 114A-114F and 116A in the verticaldirection. In some embodiments, all M1 segments 124 are placed so thatan imaginary horizontal reference line bisecting each M1 segment 124 iscollinear with an imaginary horizontal reference line bisecting acorresponding one or more of ECO base cells 106A-106F, 108A, 110A-110F,112A, 114A-114F and 116A. Other horizontal dimensions and/or or verticaldimensions for gate structures 130A, 130B and 132 are contemplated.

In some embodiments, when one or more ECO base cells are programmed(transformed), a result is one or more corresponding ECO programmedcells. Also as a result, the one or more intra-ECO-base-cell connectionswhich are altered consequently include at least one connection to acorresponding metallization segment in the M1 layer. In someembodiments, when routing an ECO programmed cell, one or more inter-cellconnections between the ECO programmed cell and one or more standardfunctional cells are established. At least one of the inter-cellconnections is a connection to an M1 segment.

During global routing, some of the line segments in the M1 layer areintended for use as straps (M1 straps). In some embodiments, some of theM1 straps are connected to the system voltage, VDD. In some embodiments,some of the M1 straps are connected to the system ground, VSS. In someembodiments, the strap segments span multiple rows in the layout.

In some embodiments, within a logic area of the layout, the M1 strapsare regularly spaced apart, which is described as the pitch of the M1straps, P_(M1-STRAP). In some embodiments, the pitch of the M1 straps,P_(M1-STRAP) is a multiple of the pitch of the metallization segments,P_(MET-SEG). Returning to FIG. 1A, within logic area 104, M1 segments120A, 120B, 122A and 122B are intended for use as strap segments. Assuch, M1 segments 120A and 120B represent a first strap in the M1 layer,and M1 segments 122A and 122B represent a second strap in the M1 layer.In FIGS. 1A-1C, each strap includes two M1 segments, e.g., the firststrap includes M1 segments 120A and 120B, the second strap segmentincludes M1 segments 122A and 122B, and the like. In some embodiments,other quantities of M1 segments are intended for use as strap segments.In some embodiments, the first M1 strap is connected to the systemvoltage, VDD, and the second M1 strap is connected to the system ground,VSS.

By contrast, the multiple instances of M1 segment 124 are intended foruse as non-strap segments. It is to be recalled that a strap is one ormore segments in a metallization layer which carry an operationalvoltage, e.g., VDD, VSS, or the like. Accordingly, in some embodiments,a non-strap segment in a metallization layer is a segment that is notdirectly connected to a strap segment. Hence, a non-strap segment doesnot carry an operational voltage, e.g., VDD, VSS, or the like. In someembodiments, M1 non-strap segments are used for connecting componentswithin a given ECO base cell or making connections between the given ECObase cell and one or more other standard cells. The one or moreintra-ECO-base-cell connections which are altered during programminginclude at least one connection to a corresponding one or more instancesof M1 non-strap segment 124. In some embodiments, when routing an ECOprogrammed cell to establish one or more inter-cell connections betweenthe ECO programmed cell and one or more standard functional cells, atleast one of the inter-cell connections is a connection to an instanceof M1 non-strap segment 124.

To produce semiconductor device feature sizes smaller than can beachieved using a single optical lithographic exposure, a multipleoptical lithographic exposure (OLE) technique is used. In general, adual OLE technique will produce feature sizes smaller than a single OLEtechnique, a triple OLE technique will produce feature sizes smallerthan a dual OLE technique, and so on. The number of OLEs is generallyreferred to as the number of masking (or mask) patterns (or maskcolors). Herein, the number of masking patterns/colors is referred to asCLR, where CLR is a positive integer.

In some embodiments, layout 100A is formed using a multiple OLEtechnique. In some embodiments, layout 100A is formed using a multipleOLE technique in which CLR is an odd number. In some embodiments, layout100A is formed using a triple OLE technique, where CLR=3. In someembodiments, layout 100A is formed using a multiple OLE technique inwhich CLR is an even number. In some embodiments, layout 100A is formedusing a dual OLE technique, where CLR=2. It is noted that FIG. 1Aassumes a circumstance in which a dual OLE technique is used, i.e.,CLR=2.

FIG. 1B is a layout 100A, corresponding to layout 100A, showingallotment of each metallization segment to one of a corresponding one ormore masking patterns/colors, in accordance with some embodiments.

Layout 100B is a simplified version of layout 100A of FIG. 1A. As inFIG. 1A, in FIG. 1B, CLR=2. Accordingly, in layout 100B, each of M1segments 120A, 120B, 122A and 122B, and each of the multiple instancesof M1 segment 124, have been allotted to a corresponding one of twomasking patterns/colors, namely a ‘red’ pattern/color and a ‘green’pattern color. Among others, the red pattern/color includes M1 strapsegments 120A and 122A. Among others, the green pattern/color includesM1 strap segments 120B and 122B.

In addition to FIG. 1B, only FIG. 5C shows masking patterns/colors. Theother figures do not show masking patterns/colors.

Returning to FIG. 1A, when placing ECO base cells into a row of alayout, it is desired to reduce gaps between adjacent ECO base cells.Such gaps represent wasted space. For example, a disadvantageousconsequence of wasted space is that the transistor density of asemiconductor device is reduced. Also, placement of ECO base cells intoa row of a layout is simplified if the ECO base cells are fixed notmerely in height but also in width. In some embodiments, a library ofstandard cells includes sub-libraries of ECO base cells, where eachsub-library includes ECO base cells of the same width as well as thesame height.

In some embodiments, a pitch of the ECO base cells, P_(ECOB) (orP_(SPARE)), is evenly divisible into the pitch of the M1 straps,P_(M1-STRAP) (or more generally P_(STRAP)), such that pitch P_(ECOB) isselected from a set, Θ, of positive integer values, θ, and

P _(ECOB)∈{θ}, where 0=P _(M1-STRAP) mod θ  (1)

where {θ}=Θ; P_(M1-STRAP) and P_(ECOB) are positive integers; and2<θ<P_(M1-STRAP). and thus P_(ECOB)<P_(M1-STRAP). It is noted that anECO base cell having P_(ECOB)=3 is the minimum width sufficient to forma transistor when the ECO base cell is programmed.

In some embodiments, pitch P_(ECOB) of the ECO base cells is chosen tobe the smallest member of the set Θ, i.e., the smallest value of θ, suchthat:

P _(ECOB)=min{θ}  (2)

In FIG. 1A, for simplicity of illustration, pitch P_(M1-STRAP)=36, pitchP_(ECOB)=6 and the number of ECO base cells between adjacent M1 straps(M1 segment pairs 120A & 120B and 122A & 122B) is shown as six (6). Moreparticularly, pitch P_(M1-STRAP)=36 indicates that there are 36 M1segments in the space between the start of one strap and the beginningof the next strap. For example, counting along the horizontal directionfrom left to right in FIG. 1A, there is a total of 36 M1 segments fromM1 segment 120A through and including the rightmost instance of M1segment 124 in, e.g., ECO base cell 106F. Pitch P_(ECOB)=6 indicatesthat there are 6 M1 segments in the space between the start of one ECObase cell and the beginning of the next ECO base cell. For example,counting along the horizontal direction from left to right in FIG. 1A,in any one of ECO base cells 106A-106F, 108A, 100A-110F, 112A, 114A-114and 116A, there is a total of 6 M1 segments, e.g., counting from left toright in base cell 106A, there are six instances of M1 segment 124). Thepossible values for θ that satisfy Equation (1), i.e., the possiblevalues of θ which divide evenly into P_(M1-STRAP), are 1, 2, 3, 4, 6, 9,12, 18 and 36, where the possible values are referred to as the setcalled Θ, where each member of the set Θ is represented by the symbol θ,and the set Θ is shown in set notation as Θ={θ}, and more particularlyΘ={θ}={1, 2, 3, 4, 6, 9, 12, 18, 36}, with P_(ECOB)=θ=6 having beenchosen for FIG. 1A. Other values for pitch P_(M1-STRAP) and/or pitchP_(ECOB) are contemplated, and thus other numbers of ECO base cellsbetween adjacent M1 straps are contemplated as well.

Example

As an example, assume that P_(M1-STRAP)=30. More particularly, pitchP_(M1-STRAP)=30 indicates that there are 30 M1 segments along thehorizontal direction in the space between the start of one strap and thebeginning of the next strap. The possible values for θ that satisfyEquation (1), i.e., the possible values of 0 which divide evenly intoP_(M1-STRAP), are {θ}={1, 2, 3, 5, 6, 10, 15, 30}. Recalling that2<θ<P_(M1-STRAP), accordingly θ=1, θ=2 and θ=30 must be discarded.Hence, P_(ECOB)=θ=3 for the given Example. Pitch P_(ECOB)=3 indicatesthat there are 3 M1 segments along the horizontal direction in the spacebetween the start of one ECO base cell and the beginning of the next ECObase cell.

In some embodiments, a reference edge of an ECO base cell aligns with aselected one of the masking patterns/colors. In some embodiments, thereference edge of each ECO base cell aligns with a center of theselected masking pattern/color. For example, in FIG. 1B, the referenceedge of the ECO base cells is the left edge, and the left edge alignswith center of a corresponding portion of the ‘red’ mask color. In someembodiments, to achieve abutment when placing ECO base cells into a rowof a layout and thereby avoid gaps between adjacent ECO base cells,pitch P_(ECOB) of the ECO base cells is chosen to be consistent with theeven/odd status of the number of masking patterns/colors CLR. Hereafter,the even/odd-status-matching pitch will be referred to as PM_(ECOB). IfCLR is even, i.e., if 0=CLR mod 2, then the value selected for PM_(ECOB)should be even. If CLR is odd, i.e., if 1=CLR mod 2, then the valueselected for PM_(ECOB) should be odd. In FIGS. 1A-1B, pitch P_(ECOB) iseven (P_(ECOB)=6) and CLR is even (CLR=2) as noted, the left edge ofeach ECO base cell has been selected as the reference edge, and the redpattern has been selected for alignment with the reference edge of eachECO base cell. Because pitch P_(ECOB) is even (P_(ECOB)=6) and CLR iseven (CLR=2) rather than odd, there are no gaps between adjacent ECObase cells in FIGS. 1A-1B. In contrast, FIGS. 5A-5C (discussed below)show gaps between adjacent ECO base cells.

The values of θ which can satisfy the additional requirement of matchingthe even/odd status of CLR will be a subset of the set Θ, i.e., a subsetof {θ}. To help distinguish the subset from {θ}, the subset will bereferred to as the set Δ of positive integer values, δ, and where Δ⊂Θ.,i.e., {δ}⊂{θ}. As such, pitch PM_(ECOB) is:

$\begin{matrix}{{{PM}_{ECOB} \in \Delta},{{{where}\mspace{14mu} \Delta} = \left\{ \delta \right\}}} & (3) \\{\left\{ \delta \right\} = \begin{pmatrix}{0 = {P_{{M\; 1} - {STRAP}}{mod}\; \delta}} \\{AND} \\{0 = {\delta \; {mod}\; {CLR}}}\end{pmatrix}} & (4)\end{matrix}$

where 2<δ<P_(M1-STRAP).

In some embodiments, PM_(ECOB) is chosen to be the smallest member ofthe set Δ that matches the even/odd status of CLR, i.e., the smallestvalue of δ that matches the even/odd status of CLR, such that:

PM _(ECOB)=min{δ}  (5)

Example

As a variation of the above Example, in addition to assuming thatP_(M1-STRAP)=30, also assume that the selected multiple OLE technique isa dual OLE technique such as in FIGS. 1A-1B such that CLR=2. Withouttaking into consideration the even/odd status of CLR, the possiblevalues for θ that satisfy Equation (1), i.e., the possible values of θwhich divide evenly into P_(M1-STRAP) are 1, 2, 3, 5, 6, 10, 15 and 30,where the possible values are referred to as the set called Θ, whereeach member of the set Θ is represented by the symbol θ, and the set Θis shown in set notation as Θ={θ}, and more particularly Θ={θ}={1, 2, 3,5, 6, 10, 15, 30}. Here, however, the even/odd status of CLR is beingtaken into consideration. Here, CLR=2 and thus the even/odd status ofCLR is even because 0=CLR mod 2=2 mod 2. As such, the subset of {θ},namely {δ}, which satisfies Equation (4), i.e., for which all membersmatch the even/odd status of CLR (here, CLR being even), is {δ}={2, 6,10, 30}. Applying Equation (5), and recalling that 2<δ<P_(M1-STRAP),accordingly δ=2 and δ=30 must be discarded. Hence, PM_(ECOB)=6 in thegiven Example.

Example

As another variation of the first Example above, in addition to assumingthat P_(M1-STRAP)=30, also assume that the selected multiple OLEtechnique is a triple OLE technique such that CLR=3. Without taking intoconsideration the even/odd status of CLR, the possible values for θ thatsatisfy Equation (2), i.e., the possible values of θ which divide evenlyinto P_(M1-STRAP) are {θ}={1, 2, 3, 5, 6, 10, 15, 30}. Here, however,the even/odd status of CLR is being taken into consideration. Here,CLR=3 and thus the even/odd status of CLR is odd because 1=CLR mod 2=3mod 2. As such, the subset of {θ}, namely {δ} which satisfies Equation(4), i.e., for which all members match the even/odd status of CLR (here,CLR being odd), is {δ}={1, 3, 5, 15}. Applying Equation (5), andrecalling that 2<δ<P_(M1-STRAP), accordingly δ=1 is discarded. Hence,PM_(ECOB)=3 in the given Example.

FIG. 1C is a layout 100C, corresponding to layout 100A, showing reservedregions in the ECO base cells, in accordance with some embodiments.

When a given quantity of M1 segments in an ECO base cell is reserved fora particular purpose, then the given quantity of M1 segments are usablefor the particular purpose. For example, reserving the given quantity ofM1 segments in an ECO base cell for a strap indicates that the givenquantity of M1 segments will be used for a strap.

When a region in an ECO base cell is reserved for a particular purpose,then the M1 segments in the reserved region are usable for theparticular purpose. For example, reserving a region in an ECO base cellfor a strap indicates that M1 segments in the reserved region will beused for a strap. In some embodiments, the same region in each ECO basecell is reserved for the same purpose.

Layout 100C is a simplified version of layout 100A of FIG. 1A albeit onein which a reserved region and an unreserved region in each ECO basecell has been indicated. In some embodiments, relative to the M1 layer,all of the ECO base cells in a library of standard cells are arranged toreserve the same number of one or more M1 segments for use as M1 strapsegments. Though not every ECO base will have an M1 strap routed throughthe ECO base cell, nevertheless reserving the same number of M1 segmentsin each ECO base cell simplifies placing any given ECO base cell into arow of a layout.

In some embodiments, in addition to reserving the same number of M1segments, each ECO base cell in a library of standard cells allots thesame region within the cell to be the region in which the reservednumber of M1 segments are located. Reserving the same region in each ECObase cell for M1 segments further simplifies placing any given ECO basecell into a row of a layout because, e.g., it eliminates the possibleconflict that might otherwise occur if M1 segments that were intendedfor non-strap purposes are then also needed for use as strap segments.

In FIG. 1C, the reserved regions are left-edge aligned. Moreparticularly, reserved regions 140A, 140B, 140C, 140D, 140E and 140F(140A-140F), 144A, 150A-150F, 154A, 160A-160F and 164A are located incorresponding ECO base cells 106A-106F, 108A, 110A-110F, 112A, 114A-114Fand 116A. Left edges of reserved regions 140A, 140B, 140C, 140D, 140Eand 140F (140A-140F), 144A, 150A-150F, 154A, 160A-160F and 164A arealigned with left edges of corresponding ECO base cells 106A-106F, 108A,110A-110F, 112A, 114A-114F and 116A. The M1 segments in reserved regions140A-140F, 144A, 150A-150F, 154A, 160A-160F and 166A are intended foruse as M1 strap segments.

Also, in ECO base cells 106A-106F, 108A, 110A-110F, 112A, 114A-114F and116A, corresponding regions 142A-142F, 146A, 152A-152F, 156A, 162A-162Fand 166A are unreserved regions. None of unreserved regions 142A-142F,146A, 152A-152F, 156A, 162A-162F and 166A is divided in two parts bycorresponding reserved regions 140A, 140B, 140C, 140D, 140E and 140F(140A-140F), 144A, 150A-150F, 154A, 160A-160F and 164A.

The M1 segments in unreserved regions 142A-142F, 146A, 152A-152F, 156A,162A-162F and 166A are intended for use as M1 non-strap segments. InFIG. 1C, corresponding ones of the multiple instances of M1 segment 124(not shown in FIG. 1C, but see FIGS. 1A-1B) are located in unreservedregions 142A-142F, 146A, 152A-152F, 156A, 162A-162F and 166A.

FIG. 2 is a layout 200, for a semiconductor device, showing reservedregions in the ECO base cells, in accordance with some embodiments.

Layout 200 is a variation of layout 100C of FIG. 1C. In someembodiments, the M(i) layer is M1. In FIG. 2, M(i) is M1. Similar toFIGS. 1A-1C, in FIG. 2 (as an example), pitch P_(M1-STRAP)=36, pitchP_(ECOB)=6, CLR=2 and the number of ECO base cells between adjacent M1straps (M1 segment pairs 120A & 120B and 122A & 122B) is shown as six(6).

In FIG. 2, the reserved regions are right-edge aligned, whereas FIG. 1Cshows left-edge alignment. More particularly, in FIG. 2, reservedregions 240A-240F, 244A, 250A-250F, 254A, 260A-260F and 264A are locatedin corresponding ECO base cells 206A-206F, 208A, 210A-210F, 212A,214A-214F and 216A. Right edges of reserved regions 240A-240F, 244A,250A-250F, 254A, 260A-260F and 264A are aligned with right edges ofcorresponding ECO base cells 206A-206F, 208A, 210A-210F, 212A, 214A-214Fand 216A. The M1 segments in reserved regions 240A-240F, 244A,250A-250F, 254A, 260A-260F and 266A are intended for use as M1 strapsegments.

In FIG. 2, M1 strap segments 220A and 220B represent a first M1 strapand are located in reserved regions 240A, 250A and 260A. M1 strapsegments 222A and 222B represent a second M1 strap segment and arelocated in reserved regions 244A, 254A and 264A. In some embodiments,the first M1 strap (represented by M1 strap segments 220A and 220B) isconnected to the system voltage, VDD, and the second M1 strap(represented by M1 strap segments 222A and 222B) is connected to thesystem ground, VSS.

Also, in ECO base cells 206A-206F, 208A, 210A-210F, 212A, 214A-214F and216A, corresponding regions 242A-242F, 246A, 252A-252F, 256A, 262A-262Fand 266A are unreserved regions. None of the reserved regions 242A-242F,246A, 252A-252F, 256A, 262A-262F and 266A is divided into two parts bycorresponding reserved regions 240A-240F, 244A, 250A-250F, 254A,260A-260F and 264A. The M1 segments in unreserved regions 242A-242F,246A, 252A-252F, 256A, 262A-262F and 266A are intended for use as M1non-strap segments.

FIG. 3A is a layout 300, for a semiconductor device, showing reservedregions in the ECO base cells, in accordance with some embodiments. FIG.3B is simplified version of layout 300 in which the reserved andunreserved regions are not shown, in accordance with some embodiments.FIG. 3C is simplified version of layout 300 in which the ECO base cellsare not shown, in accordance with some embodiments.

In some embodiments, the M(i) layer is M1. In FIGS. 3A-3C, M(i) is M1.Similar to FIGS. 1A-1C, in FIG. 2 (as an example), pitchP_(M1-STRAP)=36, pitch P_(ECOB)=6, CLR=2 and the number of ECO basecells between adjacent M1 straps (M1 segment pairs 120A & 120B and 122A& 122B) is shown as six (6).

Layout 300 is a variation of layout 100C of FIG. 1C. In FIGS. 3A-3C, thereserved regions are centered in the ECO base cells, whereas FIG. 1Ashows left-edge alignment and FIG. 2 shows right-edge alignment. Moreparticularly, reserved regions 340A-340F, 344A, 350A-350F, 354A,360A-360F and 364A are horizontally centered in corresponding ECO basecells 306A-306F, 308A, 310A-310F, 312A, 314A-314F and 316A. The M1segments in reserved regions 340A-340F, 344A, 350A-350F, 354A, 360A-360Fand 366A are intended for use as M1 strap segments.

In FIGS. 3A-3C, M1 strap segments 320A and 320B represent a first M1strap and are located in reserved regions 340A, 350A and 360A. M1 strapsegments 322A and 322B represent a second M1 strap segment and arelocated in reserved regions 344A, 354A and 364A. In some embodiments,the first M1 strap (represented by M1 strap segments 320A and 320B) isconnected to the system voltage, VDD, and the second M1 strap(represented by M1 strap segments 322A and 322B) is connected to thesystem ground, VSS.

As a result of the centering, each ECO base cell in FIGS. 3A-3C has twounreserved regions, namely a left side unreserved region and a rightside unreserved region. In ECO base cells 306A-306F, 308A, 310A-310F,312A, 314A-314F and 316A, there are: corresponding left side regions342A-342F, 346A, 352A-352F, 356A, 362A-362F and 366A which areunreserved regions; and corresponding right side regions 343A-343F,347A, 353A-353F, 357A, 363A-363F and 367A which are unreserved regions.The M1 segments in unreserved regions 342A-342F, 343A-343F, 346A, 347A,352A-352F, 353A-353F, 356A, 357A, 362A-362F, 363A-363F, 366A and 367Aare intended for use as M1 non-strap segments.

FIG. 4A is a layout 400, for a semiconductor device, of ECO base cellsrelative to line segments in an i^(th) metallization layer, M(i), inaccordance with some embodiments. FIG. 4B is a simplified version oflayout 400 in which the reserved and unreserved regions are not shown,in accordance with some embodiments. FIG. 4C is simplified version oflayout 400 in which the ECO base cells are not shown, in accordance withsome embodiments.

In some embodiments, the M(i) layer is M1. In FIGS. 4A-4C, M(i) is M1.

FIGS. 4A-4C show a different pitch P_(ECOB) relative to pitchP_(M1-STRAP) as contrasted with, e.g., FIGS. 1A-1C. Layout 400 is avariation of layout 100A of FIG. 1A. In FIGS. 4A-4C, the number of ECObase cells between adjacent M1 straps is shown as three (3). In someembodiments, in FIGS. 4A-4C, pitch P_(M1-STRAP)=36, pitch P_(ECOB)=10and CLR=2. More particularly, pitch P_(M1-STRAP)=36 indicates that thereare 36 M1 segments along the horizontal direction in the space betweenthe start of one strap and the beginning of the next strap. Forsimplicity of illustration, while M1 segments 435A-435B, 436A-436B,437A-437B and 438A-438B are shown in FIGS. 4A-4C, other M1 segments arenot shown. Pitch P_(ECOB)=10 indicates that there are 10 M1 segmentsalong the horizontal direction in the space between the start of one ECObase cell and the beginning of the next ECO base cell.

Similar to FIG. 1A, the reserved regions in FIGS. 4A and 4C areleft-edge aligned. More particularly, reserved regions 440A-440C,444A-444C, 448A-448C, 452A-452C, 460A-460C, 464A-464C, 468A-468C,472A-472C, 480A-480C, 484A-484C, 488A-488C and 492A-492C are located incorresponding ECO base cells 406A-406C, 408A-408C, 410A-410C, 412A-412C,416A-416C, 418A-418C, 420A-420C, 422A-422C, 424A-424C, 426A-426C,428A-428C and 430A-430C.

Left edges of reserved regions 440A-440C, 444A-444C, 448A-448C,452A-452C, 460A-460C, 464A-464C, 468A-468C, 472A-472C, 480A-480C,484A-484C, 488A-488C and 492A-492C are aligned with left edges ofcorresponding ECO base cells 406A-406C, 408A-408C, 410A-410C, 412A-412C,416A-416C, 418A-418C, 420A-420C, 422A-422C, 424A-424C, 426A-426C,428A-428C and 430A-430C. The M1 segments in reserved regions 440A-440C,444A-444C, 448A-448C, 452A-452C, 460A-460C, 464A-464C, 468A-468C,472A-472C, 480A-480C, 484A-484C, 488A-488C and 492A-492C are intendedfor use as M1 strap segments.

Also, in ECO base cells 406A-406C, 408A-408C, 410A-410C, 412A-412C,416A-416C, 418A-418C, 420A-420C, 422A-422C, 424A-424C, 426A-426C,428A-428C and 430A-430C, corresponding regions 442A-442C, 446A-446C,450A-450C, 454A-454C, 462A-462C, 466A-46C, 470A-470C, 474A-474C,482A-482C, 486A-486C, 490A-490C and 494A-494C are unreserved regions.

The M1 segments in reserved regions 440A, 460A and 480A are intended foruse as corresponding M1 strap segments 435A-435B. The M1 strap segmentsin reserved regions 444A, 464A and 484A are intended for use ascorresponding M1 strap segments 436A-436B. The M1 segments in reservedregions 448A, 468A and 488A are intended for use as corresponding M1strap segments 437A-437B. The M1 segments in reserved regions 452A, 472Aand 492A are intended for use as corresponding M1 strap segments438A-438B.

FIG. 5A is a layout 500A, for a semiconductor device, of ECO base cellsrelative to line segments in an i^(th) metallization layer, M(i), inaccordance with some embodiments. FIG. 5B is layout 500B, which is asimplified version of layout 500A albeit also showing wasted space, inaccordance with some embodiments.

FIG. 5C is a layout 500C, which is simplified version of layout 500Aalbeit also showing wasted space and allotment of each metallizationsegment to a corresponding masking pattern/color, in accordance withsome embodiments. In addition to FIG. 5C, FIG. 1B shows maskingpatterns/colors. The other figures do not show masking patterns/colors.

In some embodiments, the M(i) layer is M1. In FIGS. 5A-5C, M(i) is M1.Layout 500 is a variation of layout 100 of FIG. 1A. In FIGS. 5A-5C, thereserved regions (not shown) are left-edge aligned with left-edges ofECO base cells 506A-506D, 508A, 510A-510D, 512A, 514A-514D and 516A.

In some embodiments, layout 500A is formed using a multiple OLEtechnique. In some embodiments, layout 500A is formed using a multipleOLE technique in which CLR is an even number. In some embodiments,layout 500A is formed using a dual OLE technique, where CLR=2. In someembodiments, layout 500A is formed using a multiple OLE technique inwhich CLR is an odd number. In some embodiments, layout 500A is formedusing a triple OLE technique, where CLR=3. It is noted that FIGS. 5A-5Cassume a circumstance in which a triple OLE technique is used, i.e.,CLR=3.

In FIGS. 5A-5C, for simplicity of illustration, pitch P_(M1-STRAP)=36,pitch P_(ECOB)=4, and the number of ECO base cells between adjacent M1straps is shown as six (6). More particularly, pitch P_(M1-STRAP)=36indicates that there are 36 M1 segments along the horizontal directionin the space between the start of one strap and the beginning of thenext strap. Pitch P_(ECOB)=4 indicates that there are 4 M1 segmentsalong the horizontal direction in the space between the start of one ECObase cell and the beginning of the next ECO base cell. The possiblevalues for θ that satisfy Equation (1), i.e., the possible values of θwhich divide evenly into P_(M1-STRAP) are {θ}={1, 2, 3, 4, 6, 9, 12, 18,36}, with P_(ECOB)=θ=4 having been chosen for FIGS. 5A-5C. Recallingthat 2<θ<P_(M1-STRAP), accordingly θ=1, θ=2 and θ=36 must be discarded.Other values for pitch P_(M1-STRAP), pitch P_(ECOB) and/or CLR arecontemplated, and thus other numbers if ECO base cells between adjacentM1 straps are contemplated as well. In FIGS. 5A-5C, pitch P_(ECOB) iseven (P_(ECOB)=4), CLR is odd (CLR=3), the left edge of each ECO basecell has been selected as the reference edge, and the red pattern (FIG.5C) has been selected for alignment with the reference edge of each ECObase cell. The possible values for δ that satisfy Equation (4), i.e.,the possible values of δ which divide evenly into P_(M1-STRAP) AND whichare evenly divisible by CLR (CLR=3) are {δ}={3, 6, 9, 12, 18, 36}.Recalling that 2<δ <P_(M1-STRAP), accordingly δ=36 must be discarded.While θ=4 is valid relative to Equation (1), δ≠4 for Equation (4)because 0=δ mod CLR would NOT be true, i.e., 0≠4 mod 3, rather 1=4 mod3. Because of the even/odd mismatch, i.e., because pitch P_(ECOB) iseven (P_(ECOB)=4) and CLR is odd (CLR=3), FIGS. 5B-5C show: a gap 551Abetween ECO base cells 506A, 510A and 514A and corresponding ECO basecells 506B, 510B and 514B; a gap 551B between ECO base cells 506B, 510Band 514B and corresponding ECO base cells 506C, 510C and 514C; a gap551C between ECO base cells 506C, 510C and 514C and corresponding ECObase cells 506D, 510D and 514D; a gap 551D between ECO base cells 506D,510D and 514D and corresponding ECO base cells 506E, 510E and 514E; agap 551E between ECO base cells 506E, 510E and 514E and correspondingECO base cells 506F, 510F and 514F; and a gap 551F between ECO basecells 506F, 510F and 514F and corresponding ECO base cells 508A, 512Aand 516A.

FIG. 6A is a flowchart of a method 600 of designing, for a semiconductordevice, a layout which includes standard spare cells, in accordance withsome embodiments.

In FIG. 6A, at block 602, a set of possible values for a pitch P_(SPARE)of standard spare cells is generated based on the pitch P_(STRAP) ofstrap lines of a metallization layer M(i) in a layout for asemiconductor device. In some embodiments, M(i) is M1. Details of block602 are explained with reference to FIG. 6B. From block 602, flowproceeds to a block 604. At block 604, one member of thepossible-values-set is selected to be the pitch P_(SPARE). Details ofblock 604 are explained with reference to FIG. 6C. From block 604, flowproceeds to a block 606. At block 606, standard spare cells are placedinto a logic area of the layout according to the pitch P_(SPARE). Fromblock 606, flow proceeds to a block 608.

At block 608, in each spare cell, a portion is reserved/selected to be areserved-portion, wherein one or more of the strap lines can be formedover the reserved-portion. In some embodiments, each reserved-portionextends across the spare cell. Details of block 608 are explained withreference to FIG. 6D. From block 608, flow proceeds to a block 610. Atblock 610, one or more masks for the layout are generated based on thepitch P_(STRAP) and the pitch P_(SPARE). From block 610, flow proceedsto a block 612. At block 612, the semiconductor device is manufacturedusing the one or more masks.

FIG. 6B is a more detailed view of block 602 in method 600, inaccordance with some embodiments.

In FIG. 6B, block 602 includes a block 618. At block 618, the set ofpossible values for the pitch P_(SPARE) is also generated based on anumber of masks, CLR, which have been selected to produce themetallization layer. Details of block 618 are explained with referenceto blocks 620-624.

Block 618 includes blocks 620-624. At block 620, a first group ofcandidate positive integers is calculated, each member of the firstgroup being a positive integer being evenly divisible into the pitchP_(STRAP). From block 620, flow proceeds to a block 622. At block 622, asecond group of candidate positive integers is calculated, each memberof the second group being evenly divisible by the number of masks CLR.From block 622, flow proceeds to a block 624. At block 624, the firstand second groups are intersected to form a third group of positivecandidate integers. The third group represents the set of possiblevalues for a pitch P_(SPARE) of standard spare cells.

FIG. 6C is a further detailed view of block 604 in method 600, inaccordance with some embodiments.

In FIG. 6C, at block 630, a smallest member of the set of possiblevalues for a pitch P_(SPARE) is selected to be the pitch P_(SPARE). Insome embodiments, 2<P_(SPARE). Selecting the smallest member reducesgaps between adjacent ECO base cells, which reduces wasted space andincreases density (in terms of the number of devices per cell).

FIG. 6D is a more detailed view of block 608 in method 600, inaccordance with some embodiments.

In FIG. 6D, block 608 includes a block 640. At block 640, eachreserved-portion is located/placed such that a remaining portion of thespare cell is not divided into parts.

FIG. 7A is a flowchart of a method 700 of designing, for a semiconductordevice, a layout which includes standard functional cells and standardspare cells, in accordance with some embodiments.

In FIG. 7A, at block 702, standard functional cells are placed/arrangedto fill partially a logic area of a layout according to at least onecorresponding schematic design, which thereby leaves an unfilled spareregion in the logic area. From block 702, flow proceeds to a block 704.At block 704, a pitch P_(STRAP) of strap lines for a metallization layerM(i) is determined. In some embodiments, M(i) is M1. From block 704,flow proceeds to a block 706. At block 706, a set of possible values fora pitch P_(SPARE) of spare cells is generated based on the pitchP_(STRAP). Details of block 706 are explained with reference to FIG. 7B.From block 706, flow proceeds to a block 708. At block 708, one memberof the possible-values-set is selected to be the pitch P_(SPARE).Details of block 708 are explained with reference to FIG. 7C. From block708, flow proceeds to a block 710. At block 710, standard spare cellsare arranged/placed in the spare region according to the pitchP_(SPARE). From block 710, flow proceeds to a block 712.

At block 712, in each spare cell, a portion is reserved/selected to be areserved-portion, wherein one or more of the strap lines can be formedover the reserved-portion. In some embodiments, each reserved-portionextends across the spare cell. From block 712, flow proceeds to a block714. At block 714, each reserved-portion is located/placed such that aremaining portion of the spare cell is not divided into parts. Fromblock 714, flow proceeds to a block 716. At block 716, one or more masksfor the layout are generated based on the pitch P_(STRAP) and the pitchP_(SPARE). From block 716, flow proceeds to a block 718. At block 718,the semiconductor device is manufactured using the one or more masks.

FIG. 7B is a more detailed view of block 706 in method 700, inaccordance with some embodiments.

In FIG. 7B, block 706 includes blocks 720 and 722. At block 720, a valuefor CLR is received, where CLR represents a number of masks selected toproduce the metallization layer. From block 720, flow proceeds to ablock 722. At block 722, a set Δ of candidate positive integers δ,Δ={δ}, is calculated. Each candidate δ is evenly divisible into thepitch P_(STRAP) and each candidate δ matches an even/odd status of CLRsuch that:

$\left\{ \delta \right\} = {\begin{pmatrix}{0 = {P_{STRAP}{mod}\; \delta}} \\{AND} \\{0 = {\delta \; {mod}\; {CLR}}}\end{pmatrix}.}$

FIG. 7C is a more detailed view of block 708 in method 700, inaccordance with some embodiments.

In FIG. 7C, block 708 includes a block 724. At block 724, a smallestmember of the set Δ={δ} is chosen to be the pitch P_(SPARE) such that

P _(SPARE)=min{δ}.

FIG. 8 is a flowchart of a method 800 of designing, for a semiconductordevice, a layout which includes standard spare cells, in accordance withsome embodiments.

In FIG. 8, at block 802, relative to a layout for a semiconductordevice, a pitch P_(STRAP) of strap lines of a metallization layer M(i)and a pitch P_(SPARE) of standard spare cells are received at an inputdevice of a computer. In some embodiments, M(i) is M1. From block 802,flow proceeds to a block 804. At block 804, in each spare cell, aportion is reserved/selected to be a reserved-portion, wherein one ormore of the strap lines can be formed over the reserved-portion. In someembodiments, each reserved-portion extends across the spare cell. Fromblock 804, flow proceeds to a block 806. At block 806, eachreserved-portion is located/placed such that a remaining portion of thespare cell is not divided into parts. From block 806, flow proceeds to ablock 808. At block 808, in a spare region of a logic area, spare cellsare arranged/placed according to the pitch P_(SPARE). From block 808,flow proceeds to a block 810. At block 810, one or more masks for thelayout are generated based on the pitch P_(STRAP) and the pitchP_(SPARE). From block 816, flow proceeds to a block 818. At block 818,the semiconductor device is manufactured using the one or more masks.

FIG. 9A is a schematic view of a semiconductor device 900, in accordancewith some embodiments.

Device 900 includes an IC formed on a substrate 921. Device 900 includesa logic area 904. In some embodiments, logic area 904 is configured toprovide a higher-level functionality of device 900. In some embodiments,logic area 904 represents one or more circuits. In some embodiments,logic area 904 includes an array 970 of ECO cells and one or morenon-standard cells 951 (one or more custom cells and/or one or moremacro cells). In some embodiments, logic area 904 includes array 970 ofECO cells and one or more standard functional cells 955 organized intoone or more arrangements which provide corresponding one or morehigh-level functions. Included among non-standard cells 951 is a set ofone on or more non-standard cells 953. Included among standardfunctional cells 955 is a set of one or more standard functional cells957. Included among the ECO cells in array 970 is a set 971 of one ormore ECO cells and a set 975 of one or more ECO cells. Initially, all ofthe ECO cells in array 970 are ECO base cells because none of the ECOcells have yet to be programmed (transformed) into ECO programmed cells.As such, FIG. 9A represents an initial state of device 900 in which noneof the ECO cells in array 970 are connected (or routed) to non-standardcells 951 or standard functional cells 955.

FIG. 9B is a schematic view of the semiconductor device 900 with one ormore ECO programmed cells and one or more ECO base cells, in accordancewith some embodiments.

FIG. 9B represents a revised state of device 900. More particularly,FIG. 9B shows that set 971 of one or more ECO base cells and set 975 ofone or more ECO base cells has been programmed, which has transformedsets 971 and 975 into corresponding sets 972 and 976 of one or more ECOprogrammed cells. In some embodiments, FIG. 9B reflects an assumptionthat set 953 has failed. Accordingly, routing 974 represents connectionsthat have been made between set 972 of ECO programmed cells and logicarea 904 so that set 972 can serve (in effect) as a replacement forfailed set 953. In some embodiments, FIG. 9B reflects an assumption thatset 957 has failed. Accordingly, routing 978 represents connections thathave been made between set 976 of ECO programmed cells and logic area904 so that set 976 can serve (in effect) as a replacement for failedset 958.

FIG. 10 is a flow chart of a method 1000 of designing or manufacturing asemiconductor device, in accordance with some embodiments. The followingdescription of the method of FIG. 10 will be made with reference toFIGS. 9A and 9B.

In FIG. 10, at block 1005, a semiconductor device is designed ormanufactured. In some embodiments, the device of block 1005 is asemiconductor device 900 as shown in FIG. 9A. From block 1005, flowproceeds to a block 1015. At block 1015, device 900 (as designed ormanufactured) is tested. In some embodiments, logic area 904 of device900 is tested, e.g., by one or more simulations, and checked against aplurality of design rules and/or the intended specification of device900. In at least one embodiment, a test version of device 900 ismanufactured based on the initial design and then the manufactured testversion of device 900 is tested. Based on the test results of thedesigned device 900 and/or the manufactured test version of device 900,a decision is made to revise the design, e.g., because of anunacceptable timing issue, an unacceptable electromigration issue, orthe like. From block 1015, flow proceeds to a block 1025. In somecircumstances, despite the test results not triggering a revision to thedesign, a design change is requested. In such circumstances, the designchange is received and flow proceeds from block 1015 to a block 1025. Insome other circumstances, in addition to the test results triggering arevision to the design, a design change also is received. In such othercircumstances, flow similarly proceeds from block 1015 to block 1025.

At block 1025, one or more ECO base cells in array 970 are programmed ifthe test results indicate that the design is to be revised and/or adesign change has been received. For example, if the design is to berevised to replace failed set 953 and/or failed set 957 (shown in FIG.9A), then one or more ECO base cells in array 970, e.g., sets 971 and/or975 (shown in FIG. 9A), are programmed to provide the equivalentfunction of corresponding failed sets 953 and/or 957. Programming sets971 and/or 975 transforms the one or more ECO base cells in sets 971and/or 975 into corresponding sets 972 and/or 976 of one or more ECOprogrammed cells. From block 1025, flow proceeds to a block 1035. Atblock 1035, one or more ECO programmed cells in sets 972 and/or 976 arerouted (electrically connected) to corresponding one or more standardfunctional cells in logic area 904, thereby (in effect) replacing failedsets 953 and/or 957.

In at least one embodiment, one or more ECO base cells in array 970 areprogrammed and routed to modify, rather than replace, one or more cells(not shown) (which have not necessarily failed) in logic area 904. In atleast one embodiment, one or more ECO base cells in array 970 areprogrammed and routed to add new functionality to logic area 904. Insome embodiments, the revised design of the IC and/or an IC manufacturedbased on the revised design are tested to determine whether furtherrevisions are to be made. In at least one embodiment, the processrepeats until determination is made that the IC is to be re-designed orthat the revised design of the IC is satisfactory for mass manufacture.

The above methods include example operations, but they are notnecessarily required to be performed in the order shown. Operations maybe added, replaced, changed order, and/or eliminated as appropriate, inaccordance with the spirit and scope of embodiments of the disclosure.Embodiments that combine different features and/or different embodimentsare within the scope of the disclosure and will be apparent to those ofordinary skill in the art after reviewing this disclosure.

In some embodiments, one or more operations of the method 1000 is/areperformed by one or more computer systems. For example, one or more ofthe operations of designing an IC, simulating a design of the IC,programming ECO base cells, and routing the ECO programmed cells to acircuit of the IC are performed by one or more computer systems.

FIG. 11 is a block diagram of an electronic design automation (EDA)system 1100 in accordance with some embodiments.

In some embodiments, EDA system 1100 is a general purpose computingdevice including a hardware processor 1102 and a non-transitory,computer-readable storage medium 1104. Storage medium 1104, amongstother things, is encoded with, i.e., stores, computer program code 1106,i.e., a set of executable instructions. Execution of instructions 1106by hardware processor 1102 represents (at least in part) an EDA toolwhich implements a portion or all of, e.g., the standard functional cellselection process, the placement process, the routing process, thetesting process and/or the overall SPRT process, and the processes asdescribed, e.g., in at least one of the methods of FIGS. 6A-6D, 7A-7C, 8and 10, in accordance with one or more embodiments (hereinafter, thenoted PROCESSES AND/OR METHODS).

Processor 1102 is electrically coupled to computer-readable storagemedium 1104 via a bus 1108. Processor 1102 is also electrically coupledto an I/O interface 1110 by bus 1108. A network interface 1112 is alsoelectrically connected to processor 1102 via bus 1108. Network interface1112 is connected to a network 1114, so that processor 1102 andcomputer-readable storage medium 1104 are capable of connecting toexternal elements via network 1114. Processor 1102 is configured toexecute computer program code (instructions) 1106 encoded incomputer-readable storage medium 1104 in order to cause system 1100 tobe usable for performing a portion or all of the noted PROCESSES AND/ORMETHODS. In one or more embodiments, processor 1102 is a centralprocessing unit (CPU), a multi-processor, a distributed processingsystem, an application specific integrated circuit (ASIC), and/or asuitable processing unit.

In one or more embodiments, computer-readable storage medium 1104 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example,computer-readable storage medium 1104 includes a semiconductor orsolid-state memory, a magnetic tape, a removable computer diskette, arandom access memory (RAM), a read-only memory (ROM), a rigid magneticdisk, and/or an optical disk. In one or more embodiments using opticaldisks, computer-readable storage medium 1104 includes a compactdisk-read only memory (CD-ROM), a compact disk-read/write (CD-R/W),and/or a digital video disc (DVD).

In one or more embodiments, storage medium 1104 stores computer programcode 1106 configured to cause system 1100 (where such executionrepresents (at least in part) the EDA tool) to be usable for performinga portion or all of the noted PROCESSES AND/OR METHODS. In one or moreembodiments, storage medium 1104 also stores information whichfacilitates performing a portion or all of the noted PROCESSES AND/ORMETHODS. In one or more embodiments, storage medium 1104 stores library1107 of standard cells including standard functional cells and standardECO base cells.

EDA system 1100 includes I/O interface 1110. I/O interface 1110 iscoupled to external circuitry. In one or more embodiments, I/O interface1120 includes a keyboard, keypad, mouse, trackball, trackpad,touchscreen, and/or cursor direction keys for communicating informationand commands to processor 1102.

EDA system 1100 also includes network interface 1112 coupled toprocessor 1102. Network interface 1112 allows system 1100 to communicatewith network 1114, to which one or more other computer systems areconnected. Network interface 1112 includes wireless network interfacessuch as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wired networkinterfaces such as ETHERNET, USB, or IEEE-1364. In one or moreembodiments, a portion or all of noted PROCESSES AND/OR METHODS., isimplemented in two or more systems 1100.

System 1100 is configured to receive information through I/O interface1110. The information received through I/O interface 1110 includes oneor more of instructions, data, design rules, libraries of standardcells, and/or other parameters for processing by processor 1102. Theinformation is transferred to processor 1102 via bus 1108. EDA system1100 is configured to receive information related to a UI through I/Ointerface 1110. The information is stored in computer-readable medium1104 as UI 1142.

In some embodiments, a portion or all of the noted PROCESSES AND/ORMETHODS is implemented as a standalone software application forexecution by a processor. In some embodiments, a portion or all of thenoted PROCESSES AND/OR METHODS is implemented as a software applicationthat is a part of an additional software application. In someembodiments, a portion or all of the noted PROCESSES AND/OR METHODS isimplemented as a plug-in to a software application. In some embodiments,at least one of the noted PROCESSES AND/OR METHODS is implemented as asoftware application that is a portion of an EDA tool. In someembodiments, a portion or all of the noted PROCESSES AND/OR METHODS isimplemented as a software application that is used by EDA system 1100.In some embodiments, a layout which includes standard cells plus ECObase cells and/or ECO programmed cells is generated using a tool such asVIRTUOSO® available from CADENCE DESIGN SYSTEMS, Inc., or anothersuitable layout generating tool.

In an embodiment, a semiconductor device includes: standard functionalcells located in a logic area; standard spare cells arranged in a spareregion of the logic area; and a metallization layer including segments,some of the segments being included in corresponding ones of thefunctional cells, some of the segments being included in correspondingones of the spare cells, and some of the segments representing straplines; and wherein a first pitch of the standard spare cells is based ona second pitch of the strap lines. In an embodiment, the first pitch issubstantially evenly divisible into the second pitch. In an embodiment,there is a group of candidate integers, each candidate integer being apositive integer greater than two, and each candidate integer beingsubstantially evenly divisible into the second pitch; the first pitch isa member of the group; and the first pitch is smaller than a largestmember of the group. In an embodiment, there is a group of candidateintegers, each candidate integer being a positive integer greater thantwo, and each candidate integer being substantially evenly divisibleinto the second pitch; and the first pitch is a smallest member of thegroup. In an embodiment, the first pitch is also based on a number ofmasks used to produce the metallization layer. In an embodiment, thereis a group of candidate integers, each candidate integer being apositive integer greater than two, each candidate integer beingsubstantially evenly divisible into the second pitch, and each candidateinteger being substantially evenly divisible by the number of masks; thefirst pitch is a member of the group; and the first pitch is smallerthan a largest member of the group. In an embodiment, there is a groupof candidate integers, each candidate integer being a positive integergreater than two, each candidate integer being substantially evenlydivisible into the second pitch, and each candidate integer beingsubstantially evenly divisible by the number of masks; and the firstpitch is a smallest member of the group. In an embodiment, in each ofthe spare cells, some of the segments are located in a reserved region;the reserved region has a same location in each spare cell; and in eachspare cell, the segments in the reserved region are reserved for use asstrap-segments.

In an embodiment, a semiconductor device includes: standard functionalcells located in a logic area; standard spare cells arranged in a spareregion of the logic area; and a metallization layer including segments,some of the segments being included in corresponding ones of thefunctional cells, some of the segments being included in correspondingones of the spare cells, and some of the segments being strap-segmentswhich represent portions of strap lines; and wherein: a first pitch ofthe standard spare cells is based on a second pitch of the strap lines;in each of the spare cells, some of the segments are located in areserved region; the reserved region has a same location in each sparecell; and in each spare cell, the segments in the reserved region arereserved for use as strap-segments. In an embodiment, long axes of thesegments extend substantially parallel to a first direction; spare cellsare located in one or more corresponding rows which extend substantiallyparallel to a second direction, the second direction being perpendicularto the first direction; each spare cell, relative to the seconddirection, includes first and second boundaries on opposite sides of thespare cell; and one of the following is true, namely the reserved regionin each strap-routing type spare cell abuts the first boundary, or thereserved region in each strap-routing type spare cell abuts the secondboundary. In an embodiment, long axes of the segments extendsubstantially parallel to a first direction; spare cells are located inone or more corresponding rows which extend substantially parallel to asecond direction, the second direction being perpendicular to the firstdirection; each spare cell, relative to the second direction, includesfirst and second boundaries on opposite sides of the spare cell; and thereserved region in each strap-routing type spare cell has a centrallocation between the first and second boundaries. In an embodiment, thefirst pitch is substantially evenly divisible into the second pitch; andthere is a group of candidate integers, each candidate integer being apositive integer greater than two, and each candidate integer beingsubstantially evenly divisible into the second pitch; the first pitch isa member of the group; and the first pitch is smaller than a largestmember of the group. In an embodiment, the first pitch is substantiallyevenly divisible into the second pitch; and there is a group ofcandidate integers, each candidate integer being a positive integergreater than two, and each candidate integer being substantially evenlydivisible into the second pitch; and the first pitch is a smallestmember of the group. In an embodiment, the first pitch is also based ona number of masks used to produce the metallization layer; and there isa group of candidate integers, each candidate integer being a positiveinteger greater than two, each candidate integer being substantiallyevenly divisible into the second pitch, and each candidate integer beingsubstantially evenly divisible by the number of masks; the first pitchis a member of the group; and the first pitch is smaller than a largestmember of the group. In an embodiment, there is a group of candidateintegers, each candidate integer being a positive integer greater thantwo, each candidate integer being substantially evenly divisible intothe second pitch, and each candidate integer being substantially evenlydivisible by the number of masks; and the first pitch is a smallestmember of the group.

In an embodiment, a semiconductor device includes: standard functionalcells located in a logic area; standard spare cells arranged in a spareregion of the logic area; and a metallization layer including segments,some of the segments being included in corresponding ones of thefunctional cells, some of the segments being included in correspondingones of the spare cells, and some of the segments representing straplines; and wherein: a first pitch of the standard spare cells is basedon a second pitch of the strap lines; and the first pitch issubstantially evenly divisible into the second pitch. In an embodiment,there is a group of candidate integers, each candidate integer being apositive integer greater than two, and each candidate integer beingsubstantially evenly divisible into the second pitch; the first pitch isa member of the group; and the first pitch is smaller than a largestmember of the group. In an embodiment, there is a group of candidateintegers, each candidate integer being a positive integer greater thantwo, and each candidate integer being substantially evenly divisibleinto the second pitch; and the first pitch is a smallest member of thegroup. In an embodiment, the first pitch is also based on a number ofmasks used to produce the metallization layer; there is a group ofcandidate integers, each candidate integer being a positive integergreater than two, each candidate integer being substantially evenlydivisible into the second pitch, and each candidate integer beingsubstantially evenly divisible by the number of masks; the first pitchis a member of the group; and the first pitch is smaller than a largestmember of the group. In an embodiment, the first pitch is also based ona number of masks used to produce the metallization layer; there is agroup of candidate integers, each candidate integer being a positiveinteger greater than two, each candidate integer being substantiallyevenly divisible into the second pitch, and each candidate integer beingsubstantially evenly divisible by the number of masks; and the firstpitch is a smallest member of the group.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

1. A semiconductor device comprising: standard functional cells locatedin a logic area; standard spare cells arranged in a spare region of thelogic area; and a metallization layer including segments, some of thesegments being included in corresponding ones of the functional cells,some of the segments being included in corresponding ones of the sparecells, and some of the segments representing strap lines; and wherein afirst pitch of the standard spare cells is based on a second pitch ofthe strap lines.
 2. The semiconductor device of claim 1, wherein: thefirst pitch is substantially evenly divisible into the second pitch. 3.The semiconductor device of claim 2, wherein: there is a group ofcandidate integers; each candidate integer being a positive integergreater than two; and each candidate integer being substantially evenlydivisible into the second pitch; the first pitch is a member of thegroup; and the first pitch is smaller than a largest member of thegroup.
 4. The semiconductor device of claim 2, wherein: there is a groupof candidate integers; each candidate integer being a positive integergreater than two; and each candidate integer being substantially evenlydivisible into the second pitch; and the first pitch is a smallestmember of the group.
 5. The semiconductor device of claim 1, wherein:the first pitch is also based on a number of masks used to produce themetallization layer.
 6. The semiconductor device of claim 5, wherein:there is a group of candidate integers; each candidate integer being apositive integer greater than two; each candidate integer beingsubstantially evenly divisible into the second pitch; and each candidateinteger being substantially evenly divisible by the number of masks; thefirst pitch is a member of the group; and the first pitch is smallerthan a largest member of the group.
 7. The semiconductor device of claim5, wherein: there is a group of candidate integers; each candidateinteger being a positive integer greater than two; each candidateinteger being substantially evenly divisible into the second pitch; andeach candidate integer being substantially evenly divisible by thenumber of masks; and the first pitch is a smallest member of the group.8. The semiconductor device of claim 1, wherein: in each of the sparecells, some of the segments are located in a reserved region; thereserved region has a same location in each spare cell; and in eachspare cell, the segments in the reserved region are reserved for use asstrap-segments.
 9. A semiconductor device comprising: standardfunctional cells located in a logic area; standard spare cells arrangedin a spare region of the logic area; and a metallization layer includingsegments, some of the segments being included in corresponding ones ofthe functional cells, some of the segments being included incorresponding ones of the spare cells, and some of the segments beingstrap-segments which represent portions of strap lines; and wherein: afirst pitch of the standard spare cells is based on a second pitch ofthe strap lines; in each of the spare cells, some of the segments arelocated in a reserved region; the reserved region has a same location ineach spare cell; and in each spare cell, the segments in the reservedregion are reserved for use as strap-segments.
 10. The semiconductordevice of claim 9, wherein: long axes of the segments extendsubstantially parallel to a first direction; spare cells are located inone or more corresponding rows which extend substantially parallel to asecond direction, the second direction being perpendicular to the firstdirection; each spare cell, relative to the second direction, includesfirst and second boundaries on opposite sides of the spare cell; and oneof the following is true: the reserved region in each strap-routing typespare cell abuts the first boundary; or the reserved region in eachstrap-routing type spare cell abuts the second boundary.
 11. Thesemiconductor device of claim 9, wherein: long axes of the segmentsextend substantially parallel to a first direction; spare cells arelocated in one or more corresponding rows which extend substantiallyparallel to a second direction, the second direction being perpendicularto the first direction; each spare cell, relative to the seconddirection, includes first and second boundaries on opposite sides of thespare cell; and the reserved region in each strap-routing type sparecell has a central location between the first and second boundaries. 12.The semiconductor device of claim 9, wherein: the first pitch issubstantially evenly divisible into the second pitch; and there is agroup of candidate integers; each candidate integer being a positiveinteger greater than two; and each candidate integer being substantiallyevenly divisible into the second pitch; the first pitch is a member ofthe group; and the first pitch is smaller than a largest member of thegroup.
 13. The semiconductor device of claim 9, wherein: the first pitchis substantially evenly divisible into the second pitch; and there is agroup of candidate integers; each candidate integer being a positiveinteger greater than two; and each candidate integer being substantiallyevenly divisible into the second pitch; and the first pitch is asmallest member of the group.
 14. The semiconductor device of claim 9,wherein: the first pitch is also based on a number of masks used toproduce the metallization layer; and there is a group of candidateintegers; each candidate integer being a positive integer greater thantwo; each candidate integer being substantially evenly divisible intothe second pitch; and each candidate integer being substantially evenlydivisible by the number of masks; the first pitch is a member of thegroup; and the first pitch is smaller than a largest member of thegroup.
 15. The semiconductor device of claim 9, wherein: there is agroup of candidate integers; each candidate integer being a positiveinteger greater than two; each candidate integer being substantiallyevenly divisible into the second pitch; and each candidate integer beingsubstantially evenly divisible by the number of masks; and the firstpitch is a smallest member of the group.
 16. A semiconductor devicecomprising: standard functional cells located in a logic area; standardspare cells arranged in a spare region of the logic area; and ametallization layer including segments, some of the segments beingincluded in corresponding ones of the functional cells, some of thesegments being included in corresponding ones of the spare cells, andsome of the segments representing strap lines; and wherein a first pitchof the standard spare cells is based on a second pitch of the straplines; and the first pitch is substantially evenly divisible into thesecond pitch.
 17. The semiconductor device of claim 16, wherein: thereis a group of candidate integers; each candidate integer being apositive integer greater than two; and each candidate integer beingsubstantially evenly divisible into the second pitch; the first pitch isa member of the group; and the first pitch is smaller than a largestmember of the group.
 18. The semiconductor device of claim 16, wherein:there is a group of candidate integers; each candidate integer being apositive integer greater than two; and each candidate integer beingsubstantially evenly divisible into the second pitch; and the firstpitch is a smallest member of the group.
 19. The semiconductor device ofclaim 16, wherein: the first pitch is also based on a number of masksused to produce the metallization layer; there is a group of candidateintegers; each candidate integer being a positive integer greater thantwo; each candidate integer being substantially evenly divisible intothe second pitch; and each candidate integer being substantially evenlydivisible by the number of masks; the first pitch is a member of thegroup; and the first pitch is smaller than a largest member of thegroup.
 20. The semiconductor device of claim 16, wherein: the firstpitch is also based on a number of masks used to produce themetallization layer; there is a group of candidate integers; eachcandidate integer being a positive integer greater than two; eachcandidate integer being substantially evenly divisible into the secondpitch; and each candidate integer being substantially evenly divisibleby the number of masks; and the first pitch is a smallest member of thegroup.